PHYSIOLOGY OF THE INVERTEBRATA. 55 



csecal appendages. The ducts from these appendages- open 

 into the anterior end of the alimentary canal. These caecal 

 appendages are not present in any of the other Australian 

 forms mentioned above. The anus in these forms is situated 

 behind or above the caudal claws. For a further description 

 of the ■Gladocera the reader is referred to an excellent paper, 

 entitled "Oversigt af Norges Crustaceer med forelobige 

 Bemeerkninger over de nye eller mindre bekjendte Arter," 

 by Dr. Sars.* 



(24) The Ostracoda. — " The alimentary canal of the Ostra- 

 coda is provided anteriorly with an apparatus of hard parts 

 resembling in many respects the gastric armature of the 

 Isapoda, aad gives rise to two hepatic c^ca." 



In Cyprinotus dentato-marginatus, the alimentary canal 

 consists of three principal parts : a narrow, muscular oeso- 

 phagus ascending almost perpendicularly from the oral aper- 

 ture, the intestine proper, and a very short rectum opening 

 just in front of the caudal rami. "The intestine proper 

 exhibits two considerable dilatations, the anterior, lying in 

 the foremost part of the body, almost globular in form, the 

 posterior somewhat larger and more oval, both defined by a 

 well-marked median instriction, just above the great adductor 

 muscle of the shell. From the anterior division of the in- 

 testine two slender csecal appendages are given off, each 

 being received between the lamellae of the corresponding 

 valve and running diagonally backwards to the infero-posteal 

 corner." These csecal appendages, of a green colour, are, 

 d, priori, pancreatic in function. The kidney or shell -gland 

 in the Ostracoda is very small.! 



(25) The Copepoda. — The mouth leads into a straight and 

 simple alimentary canal. In Cyclops, which is probably the 

 most common form of the Copepoda, there is no distinct 



* Ghristiania Videmkahs—Selshabs Forkandlinyer, 1890, No. i, pp. 30-53. 



+ For a detailed description of many genera and species of the Ostracoda^ 

 see a paper by Dr. G. S. Brady, F.B.S., in the Transactions of the Boyal 

 Society of Edinburgh, vol. 35, p. 489 ; and one by Dr. Sars in Christ. Vidensk 

 Selsk. Forhandi, 1S89, No. 8, pp. 5-58 ; and 1890, No. i, pp. 54-76. 



